From 85dbe3f2049dce7d43a1bd956d622f4ff5c0c156 Mon Sep 17 00:00:00 2001
From: Alexei Sheplyakov <varg@theor.jinr.ru>
Date: Mon, 25 Aug 2008 19:08:36 +0400
Subject: [PATCH] parser: improve error reporting a little bit.

Introduce class 'parse_error' (which contain some info about location of
the error) and throw it on parse errors.

N.B.: the actual info is a bit inaccurate because lexer doesn't track
the location properly yet.
---
 ginac/parser/debug.hpp  | 13 +++++++++++++
 ginac/parser/lexer.cpp  | 14 ++++++++++++++
 ginac/parser/lexer.hpp  |  3 +++
 ginac/parser/parser.cpp | 20 ++++++--------------
 ginac/parser/parser.hpp | 12 ++++++++++++
 5 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/ginac/parser/debug.hpp b/ginac/parser/debug.hpp
index a43cc7ad..5221580d 100644
--- a/ginac/parser/debug.hpp
+++ b/ginac/parser/debug.hpp
@@ -20,6 +20,19 @@ do { \
 	throw exception(err.str()); \
 } while (0)
 
+#define Parse_error_(message) \
+do { \
+	std::ostringstream err; \
+	err << "GiNaC: parse error at line " << scanner->line_num << \
+		", column " << scanner->column << ": "; \
+	err << message << std::endl; \
+	err << '[' << __PRETTY_FUNCTION__ << "(" << __FILE__ << ':' << __LINE__ << ")]" << std::endl; \
+	throw parse_error(err.str(), scanner->line_num, scanner->column); \
+} while (0)
+
+#define Parse_error(message) \
+	Parse_error_(message << ", got: " << scanner->tok2str(token))
+
 #define bug(message) bail_out(std::logic_error, message)
 
 #define dout(condition, message) \
diff --git a/ginac/parser/lexer.cpp b/ginac/parser/lexer.cpp
index 894a2ad8..d8c49b8c 100644
--- a/ginac/parser/lexer.cpp
+++ b/ginac/parser/lexer.cpp
@@ -129,5 +129,19 @@ void lexer::switch_input(std::istream* in)
 	c = ' ';
 }
 
+/// Symbolic name of current token (for error reporting)
+std::string lexer::tok2str(const int tok) const
+{
+	switch (tok) {
+		case lexer::token_type::identifier:
+		case lexer::token_type::number:
+			return std::string("\"") + str + "\"";
+		case lexer::token_type::eof:
+			return std::string("EOF");
+		default:
+			return std::string("\"") + char(tok) + "\"";
+	}
+}
+
 } // namespace GiNaC
 
diff --git a/ginac/parser/lexer.hpp b/ginac/parser/lexer.hpp
index b53d08f3..0a00ed39 100644
--- a/ginac/parser/lexer.hpp
+++ b/ginac/parser/lexer.hpp
@@ -37,6 +37,9 @@ public:
 
 		};
 	};
+	
+	/// Symbolic name of the token (for error reporting)
+	std::string tok2str(const int tok) const;
 };
 
 } // namespace GiNaC
diff --git a/ginac/parser/parser.cpp b/ginac/parser/parser.cpp
index b33261c2..1e905cf5 100644
--- a/ginac/parser/parser.cpp
+++ b/ginac/parser/parser.cpp
@@ -30,7 +30,7 @@ ex parser::parse_identifier_expr()
 				break;
 
 			if (token != ',')
-				throw std::invalid_argument("Expected ')' or ',' in argument list");
+				Parse_error("expected ')' or ',' in argument list");
 
 			get_next_tok();
 		}
@@ -40,9 +40,8 @@ ex parser::parse_identifier_expr()
 	prototype the_prototype = make_pair(name, args.size());
 	prototype_table::const_iterator reader = funcs.find(the_prototype);
 	if (reader == funcs.end()) {
-		bail_out(std::invalid_argument,
-			"no function \"" << name << "\" with " << args.size()
-			<< " arguments");
+		Parse_error_("no function \"" << name << "\" with " <<
+			     args.size() << " arguments");
 	}
 	ex ret = reader->second(args);
 	return ret;
@@ -55,7 +54,7 @@ ex parser::parse_paren_expr()
 	ex e = parse_expression();
 
 	if (token != ')')
-		throw std::invalid_argument("parser::parse_paren_expr: expected ')'");
+		Parse_error("expected ')'");
 	get_next_tok();  // eat ).
 	return e;
 }
@@ -74,10 +73,7 @@ ex parser::parse_unary_expr(const int s)
 		case '+':
 			return v;
 		default:
-			throw std::invalid_argument(
-					std::string(__func__)
-					+ ": invalid unary operator \""
-					+ char(s) + "\"");
+			Parse_error_("invalid unary operator \"" << char(s) << "\"");
 	}
 }
 
@@ -98,12 +94,8 @@ ex parser::parse_primary()
 		case lexer::token_type::literal:
 			 return parse_literal_expr();
 		case lexer::token_type::eof:
-			 bail_out(std::invalid_argument, "got EOF while parsing the expression");
 		default:
-			 bail_out(std::invalid_argument, "unknown token " <<
-				token << " (\"" << 
-				(token ? std::string("") + char(token) : "NULL")
-				<< "\")");
+			 Parse_error("unexpected token");
 	}
 }
 
diff --git a/ginac/parser/parser.hpp b/ginac/parser/parser.hpp
index 81b78476..3e10b8fc 100644
--- a/ginac/parser/parser.hpp
+++ b/ginac/parser/parser.hpp
@@ -9,6 +9,18 @@ namespace GiNaC
 
 class lexer;
 
+class parse_error : public std::invalid_argument
+{
+public:
+	const std::size_t line;
+	const std::size_t column;
+	parse_error(const std::string& what_,
+		    const std::size_t line_ = 0,
+		    const std::size_t column_ = 0) throw () :
+		std::invalid_argument(what_), line(line_), column(column_)
+	{ }
+};
+
 /**
  * Recursive descent parser for GiNaC expressions.
  */
-- 
2.44.0